Third party investigations should be initiated immediately upon referral by the adoptive parent. This would involve sending someone to the site of abandonment, asking questions, interviewing key parties, putting out radio ads (radios are a very common way to spread news and they are easily accessible) for 3-6 months after abandonment. Why? Because someone knows the story of the child. The more time goes by the more that story is forgotten or the harder it is to trace down those who know the story. In the end, it is the adoptive parent in the visa interview, not the agency.
Not only is the adoptive parent responsible for investigating the story of their child, but so is the agency/organization. As I have said over and over again here, the stories of the police and social services must be independently verified by them as well. The organization you are with, the agency you are with also needs to investigate the story. You are paying them to help you adopt a child that is an orphan. The story and approval of the commune is not enough. The story of the orphanage director is not enough. It must be investigated independently and there must be a good paper trail documenting that investigation.
The responsibility is on the adoptive parent and on the agency or organization. An investigation shouldn't wait until the embassy visa appointment when you are fully in love with the child that you consider your child. It should be done before so you can go to your interview with confidence.
If these investigations are done and they are done well, when you get to your embassy interview, you have the assurance that the child you are adopting is indeed a child in need of international adoption. Their investigation of the orphan status is smoother and quicker because there is a good paper trail and investigation to consider.
Remember, you may have great paperwork when you submit your visa application. But in the end, that doesn't matter. What matters is that the paperwork is TRUE. And the most important way you can verify that is by independent 3rd party investigators. Because what matters most, is that children are not exploited for gain or taken from families that want them and that may not even know about the adoptions. What matters most is that those children that truly need international adoption are the ones being adopted and those that need to be reunited with their families are able to go back to them.